# US 6,117,309 A · Method of rerefining waste oil by distillation and extraction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,117,309 A - Document ID: US6117309A - Status: Granted - Kind: A - Application number: 08/925,279 - Filed: 1997-09-08 - Granted: 2000-09-12 - Earliest claimed: 1997-09-08 - Assignees: ProbeX Inc. - Inventors: Alexander D. B. Daspit; Martin MacDonald; Thomas G. Murray - Web page: https://patentgrep.com/patent/US6117309A ## CPC - C10M 175/0033: {using distillation processes; devices therefor} - C10M 175/005: {using extraction processes; apparatus therefor} - C10M: LUBRICATING COMPOSITIONS (well drilling compositions C09K8/02); USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION (mould release, i.e. separating, agents for metals B22C3/00, for plastics or substances in a plastic state, in general B29C33/56, for glass C03B40/02; textile lubricating compositions D06M11/00, D06M13/00, D06M15/00; immersion oils for microscopy G02B21/33) ## Abstract A process for recovering a base oil of lubricating viscosity from used oil in which, following optional pretreatment, used oil is re-refined by distilling it in distillation apparatus having multiple theoretical plates. Impurities are then extracted from the lube range distillate fraction or fractions with a liquid extractant such as N-Methyl-2-Pyrrolidone (NMP) at a temperature below the temperature, if any, of complete miscibility of the extractant and the oil. The oil and extractant are then separated whereupon the extractant is re-used in the process and the oil is subject to further treatment, as necessary, for targeted uses. ## Claims ### Claim 1 A process for recovering base oil of lubricating viscosity from used oil, said process comprising the steps of: distilling said used oil in a distillation apparatus comprising a packed column; withdrawing at least a portion of at least one distillate fraction from said distillation apparatus for further finishing; delivering at least a portion of said at least one withdrawn distillation fraction for further finishing; extracting impurities from at least one said withdrawn distillate fraction with a liquid extractant; removing at least a major portion of said extractant, and impurities dissolved therein, from said withdrawn distillate fraction; wherein said distillation apparatus has more theoretical plates than distillate fractions being withdrawn from said distillation apparatus for further finishing. ### Claim 2 (depends on 1) A process as in claim 1, wherein said distillation apparatus comprises a vacuum column operating under reduced pressure. ### Claim 3 (depends on 2) A process as in claim 2, wherein said vacuum column comprises at least one of a random packing and a structured packing. ### Claim 4 (depends on 1) A process as in claim 1, further comprising a step of pretreating said used oil to remove entrained water and volatile low boiling components from said used oil. ### Claim 5 (depends on 1) A process as in claim 1, further comprising a step of pretreating said used oil to reduce said used oil's propensity to foul said distillation apparatus. ### Claim 6 (depends on 5) A process as in claim 5, wherein said step of pretreating said used oil to reduce fouling comprises a chemical treatment of the oil. ### Claim 7 (depends on 5) A process as in claim 5, wherein said step of pretreating said used oil to reduce fouling comprises thermal treatment of the oil at a temperature in excess of 400.degree. F. for an average residence time of at least ten minutes. ### Claim 8 (depends on 1) A process as in claim 1, wherein the liquid extractant comprises a polar organic solvent. ### Claim 9 (depends on 8) A process as in claim 8, wherein the polar organic solvent is N-Methyl-2-Pyrrolidone. ### Claim 10 (depends on 1) A process as in claim 1, wherein said distillation apparatus has more than one and one half theoretical plates per distillate fraction being withdrawn from said distillation apparatus. ### Claim 11 (depends on 1) A process as in claim 1, wherein said distillation apparatus has more than two theoretical plates per distillate fraction being withdrawn from said distillation apparatus. ### Claim 12 (depends on 1) A process as in claim 1, wherein said distillation apparatus has more than three theoretical plates per distillate fraction being withdrawn from said distillation apparatus. ### Claim 13 A process for recovering base oil of lubricating viscosity from used oil, said process comprising the steps of: distilling said used oil in a distillation apparatus comprising a packed column; withdrawing at least a portion of at least two distillate fractions from said distillation apparatus for further treatment; extracting impurities from at least one of said withdrawn distillate fractions with a liquid extractant; removing at least a major portion of said extractant, and impurities dissolved therein, from said at least one of said withdrawn distillate fractions; wherein said distillation apparatus has more than one theoretical plate interposed between any two immediately adjacent distillate fractions withdrawn from said distillation apparatus. ### Claim 14 (depends on 13) A process as in claim 13, wherein said distillation apparatus comprises a vacuum column operating under reduced pressure. ### Claim 15 (depends on 14) A process as in claim 14, wherein said vacuum column comprises at least one of a random packing and a structured packing. ### Claim 16 (depends on 13) A process as in claim 13, further comprising a step of pretreating said used oil to remove entrained water and volatile low boiling components from said used oil. ### Claim 17 (depends on 13) A process as in claim 13, further comprising a step of pretreating said used oil to reduce said used oil's propensity to foul said distillation apparatus. ### Claim 18 (depends on 13) A process as in claim 13, wherein said step of pretreating said used oil to reduce fouling comprises a chemical treatment of the oil. ### Claim 19 (depends on 17) A process as in claim 17, wherein said step of pretreating said used oil to reduce fouling comprises thermal treatment of the oil at a temperature in excess of 400.degree. F. for an average residence time of at least ten minutes. ### Claim 20 (depends on 13) A process as in claim 13, wherein the liquid extractant comprises a polar organic solvent. ### Claim 21 (depends on 20) A process as in claim 20, wherein the polar organic solvent is N-Methyl-2-Pyrrolidone. ### Claim 22 (depends on 13) A process as in claim 13, wherein said distillation apparatus has more than one and one half theoretical plates interposed between any two immediately adjacent distillate fractions being withdrawn from said distillation apparatus. ### Claim 23 (depends on 13) A process as in claim 13, wherein said distillation apparatus has more than two theoretical plates interposed between any two immediately adjacent distillate fractions being withdrawn from said distillation apparatus. ### Claim 24 (depends on 13) A process as in claim 13, wherein said distillation apparatus has more than three theoretical plates interposed between any two immediately adjacent distillation fractions being withdrawn from said distillation apparatus. ### Claim 25 A process for recovering base oil of lubricating viscosity from used oil, said process comprising the steps of: distilling said used oil in a distillation apparatus comprising a packed column; withdrawing at least one distillate fraction and a bottoms fraction from said distillation apparatus; extracting impurities from at least one said distillate fraction with a liquid extractant; removing at least a major portion of said extractant, and impurities dissolved therein, from at least one of said withdrawn distillate fractions; wherein said distillation apparatus has more than one theoretical plate for separating the bottoms fraction from the heaviest distillate fraction from which impurities are extracted using said liquid extractant. ### Claim 26 (depends on 25) A process as in claim 25, wherein said distillation apparatus comprises a vacuum column operating under reduced pressure. ### Claim 27 (depends on 26) A process as in claim 26, wherein said vacuum column comprises at least one of a random packing and a structured packing. ### Claim 28 (depends on 25) A process as in claim 25, further comprising a step of pretreating said used oil to remove entrained water and volatile low boiling components from said used oil. ### Claim 29 (depends on 25) A process as in claim 25, further comprising a step of pretreating said used oil to reduce said used oil's propensity to foul said distillation apparatus. ### Claim 30 (depends on 29) A process as in claim 29, wherein said step of pretreating said used oil to reduce fouling comprises a chemical treatment of the oil. ### Claim 31 (depends on 29) A process as in claim 29, wherein said step of pretreating said used oil to reduce fouling comprises thermal treatment of the oil at a temperature in excess of 400.degree. F. for an average residence time of at least ten minutes. ### Claim 32 (depends on 25) A process as in claim 25, wherein the liquid extractant comprises a polar organic solvent. ### Claim 33 (depends on 32) A process as in claim 32, wherein the polar organic solvent is N-Methyl-2-Pyrrolidone. ### Claim 34 (depends on 25) A process as in claim 25, wherein said distillation apparatus has more than one and one half theoretical plates for separating the bottoms fraction from the heaviest distillate fraction withdrawn from said distillation apparatus. ### Claim 35 (depends on 25) A process as in claim 25, wherein said distillation apparatus has more than two theoretical plates for separating the bottoms fraction from the heaviest distillate fraction withdrawn from said distillation apparatus. ### Claim 36 (depends on 25) A process as in claim 25, wherein said distillation apparatus has more than three theoretical plates for separating the bottoms fraction from the heaviest distillate fraction withdrawn from said distillation apparatus. ### Claim 37 A process for recovering base oil of lubricating viscosity from used oil, said process comprising the steps of: distilling said used oil in a distillation apparatus comprising a packed column; withdrawing at least two distillate fractions from said distillation apparatus; extracting impurities from at least one said withdrawn distillate fractions with a liquid extractant; removing at least a major portion of said extractant, and impurities dissolved therein, from at least one said withdrawn distillate fractions; wherein said distillation apparatus has more than one theoretical plate for separating the lightest withdrawn distillate fraction from the immediately adjacent heavier distillate fraction from which impurities are extracted using said liquid extractant. ### Claim 38 (depends on 37) A process as in claim 37, wherein said distillation apparatus comprises a vacuum column operating under reduced pressure. ### Claim 39 (depends on 38) A process as in claim 38, wherein said vacuum column comprises at least one of a random packing and a structured packing. ### Claim 40 (depends on 37) A process as in claim 37, further comprising a step of pretreating said used oil to remove entrained water and volatile low boiling components from said used oil. ### Claim 41 (depends on 37) A process as in claim 37, further comprising a step of pretreating said used oil to reduce said used oil's propensity to foul said distillation apparatus. ### Claim 42 (depends on 41) A process as in claim 41, wherein said step of pretreating said used oil to reduce fouling comprises a chemical treatment of the oil. ### Claim 43 (depends on 41) A process as in claim 41, wherein said step of pretreating said used oil to reduce fouling comprises thermal treatment of the oil at a temperature in excess of 400.degree. F. for an average residence time of at least ten minutes. ### Claim 44 (depends on 37) A process as in claim 37, wherein the liquid extractant comprises a polar organic solvent. ### Claim 45 (depends on 44) A process as in claim 44, wherein the polar organic solvent is N-Methyl-2-Pyrrolidone. ### Claim 46 (depends on 37) A process as in claim 37, wherein said distillation apparatus has more than one and one half theoretical plates for separating the lightest withdrawn distillate fraction from the immediately adjacent heavier distillate fraction from which impurities are extracted using said liquid extractant. ### Claim 47 (depends on 37) A process as in claim 37, wherein said distillation apparatus has more than two theoretical plates for separating the lightest withdrawn distillate fraction from the immediately adjacent heavier distillate fraction from which impurities are extracted using said liquid extractant. ### Claim 48 (depends on 37) A process as in claim 37, wherein said distillation apparatus has more than three theoretical plates for separating the lightest withdrawn distillate fraction from the immediately adjacent heavier distillate fraction from which impurities are extracted using said liquid extractant. ### Claim 49 A process for recovering base oil of lubricating viscosity from used oil, said process comprising the steps of: distilling said used oil in a distillation apparatus comprising a packed column; withdrawing at least one distillate fraction and light by-product from said distillation apparatus; extracting impurities from at least one said withdrawn distillate fractions with a liquid extractant; removing at least a major portion of said extractant, and impurities dissolved therein, from at least one of said withdrawn distillate fractions; wherein said distillation apparatus has more than one theoretical plate for separating said light by-product from the immediately adjacent heavier distillate fraction from which impurities are extracted using said liquid extractant. ### Claim 50 (depends on 49) A process as in claim 49, wherein said distillation apparatus comprises a vacuum column operating under reduced pressure. ### Claim 51 (depends on 50) A process as in claim 50, wherein said vacuum column comprises at least one of a random packing and a structured packing. ### Claim 52 (depends on 49) A process as in claim 49, further comprising a step of pretreating said used oil to remove entrained water and volatile low boiling components from said used oil. ### Claim 53 (depends on 49) A process as in claim 49, further comprising a step of pretreating said used oil to reduce said used oil's propensity to foul said distillation apparatus. ### Claim 54 (depends on 33) A process as in claim 33, wherein said step of pretreating said used oil to reduce fouling comprises a chemical treatment of the oil. ### Claim 55 (depends on 53) A process as in claim 53, wherein said step of pretreating said used oil to reduce fouling comprises thermal treatment of the oil at a temperature in excess of 400.degree. F. for an average residence time of at least ten minutes. ### Claim 56 (depends on 49) A process as in claim 49, wherein the liquid extractant comprises a polar organic solvent. ### Claim 57 (depends on 56) A process as in claim 56, wherein the polar organic solvent is N-Methyl-2-Pyrrolidone. ### Claim 58 (depends on 49) A process as in claim 49, wherein said distillation apparatus has more than one and one half theoretical plates for separating said light by-product from the immediately adjacent heavier distillate fraction from which impurities are extracted using said liquid extractant. ### Claim 59 (depends on 49) A process as in claim 49, wherein said distillation apparatus has more than two theoretical plates for separating said light by-product from the immediately adjacent heavier distillate fraction from which impurities are extracted using said liquid extractant. ### Claim 60 (depends on 49) A process as in claim 49, wherein said distillation apparatus has more than three theoretical plates for separating said light by-product from the immediately adjacent heavier distillate fraction from which impurities are extracted using said liquid extractant.